Concrete mix design submittals, built from your approved mixes for the engineer to review.

Your QC manager reads the section, works out how many different placements it describes, picks the approved mix that fits each one, and pulls the strength history, trial batch reports and material certifications behind it. Then comes the slow part: finding what the section asks for that the file can't yet show, before an engineer finds it first.

In the test, AI works from copies of old projects and drafts the package: each requirement on its own line with the paragraph or drawing note it came from, the mix on your approved list that appears to answer it, the records behind that mix with their dates, and a list of what's missing. Your QC staff still choose every mix, and nothing leaves your office.

The requirements hide in more than one place. ACI 301-20, Specifications for Concrete Construction, is a reference specification that takes effect when an architect or engineer cites it, with checklists to fill in what each project needs. One fire and rescue station in Loudoun County, Virginia tells the contractor to refer to the structural drawing notes for mix designs, while wanting the submittal to show compliance with ACI 301 Section 4 and ACI 318 Chapter 5. Georgia's DOT offers three routes: request approval of specific proportions, with each material's source, specific gravities, aggregate absorption, amounts per cubic yard and proposed slump and air; use designs from an authorized ready mix plant; or use laboratory-designed proportions. Conway, Arkansas once wanted mix designs in with the bid, with and without air entrainment. A draft has to gather all of it before it can match a single mix.

Strength records have a shelf life. NRMCA's guidance on required average strength treats concrete as similar when specified strengths fall within 1,000 psi and says the record shouldn't be more than 24 months old. With no acceptable record, a conservative table usually pushes the target higher, and once a project has at least 15 strength results the producer may revise that target with the engineer's approval. The VA's master section wants a complete standard deviation analysis whenever field experience is the basis. California's hospital office, which takes mix designs to a district structural engineer for concurrence before pours, warns that break histories generally lack the batch tickets or inspection reports that would show time to placement or drum revolutions. The draft lists each record's dates, strengths and number of tests, and flags whatever looks too old or too far from the specified strength.

Trial batches carry their own homework. Under that VA section, each trial mix means at least six cylinders made to ASTM C192, three broken at 7 days and three at 28. The report lists cement, admixtures and aggregate weights per cubic yard measured dry rodded and damp loose, along with specific gravity, fineness modulus, moisture, air, water-cement ratio and slump, with a curve relating that ratio to strength. Where trial mixes are the basis, the proposed design must beat the specified strength by 1,200 psi, or 1,400 psi above 5,000 psi. The Waterville Public Library's section in Maine wanted an independent facility for trial batches, and not the lab doing field quality control unless the architect accepted it.

Certificates age on separate clocks. The VA section asks for mill test reports on cement, manufacturer's certificates for air-entraining and chemical admixtures that state chloride ion content, and a laboratory taking part in the Cement and Concrete Reference Laboratory program. Fly ash needs an ASTM C618 certificate with the mix design and again for each truckload from the source, on tests run within six months of the submittal. Once a mix is approved, no material or proportion may change without more tests and another approval. Wisconsin's site concrete section admits only the admixtures submitted with the mixture design unless the architect or engineer agrees otherwise. A new cement source or admixture can therefore reopen a package everyone thought was closed.

Sent back, or never read at all. The Waterville section wouldn't review an incomplete submittal, barred concrete production until mixes were reviewed, and gave two review cycles before the general contractor paid for more. It also wanted written hot and cold weather procedures under ACI 305.1 and 306.1, ready mix methods included. Wisconsin wants the mix design at least ten days before use, and the VA holds a meeting at least 15 days ahead of design mixes being submitted. Your reviewer, usually the QC manager or plant concrete technologist, will check that every requirement was found, each record really belongs to the mix cited, and the gap list matches what the engineer actually marked. No draft line says a mix complies. It says what was asked and what speaks to it, and stays empty where nothing does.

With your reviewer's yes, new project sections get the same drafting for about 30 days.

Each package waits for your QC manager, who chooses the mixes, finishes it and sends it along your usual path to the contractor.

The engineer of record goes on reviewing every submittal. A further job means a new decision at its own price, with monthly support to follow.